For example, Patent Document 1 discloses a plant operation apparatus that operates a plant such as water and sewage equipment. The plant operation apparatus displays current value data and past record data to be superimposed with each other on a trend graph in which a vertical axis represents a flow rate and a horizontal axis represents time.
Patent Document 1 discloses that, according to the plant operation apparatus, it is possible to compare a tendency of a current plant operation and a tendency of a past plant operation and to detect an abnormal tendency, in particular, to clearly ascertain abnormalities that occur in an unexpected fashion.